The M90 can detect short circuits in end devices (loads) that are connected to transistor outputs located on the M90 or on I/O expansion modules. Short circuits can also be detected in end-devices connected to analog outputs. Note that these features do not apply to the transistor outputs located on the M90-T1 and M90-T1-CAN, or the analog output located on the M90-TA2-CAN.

If a short-circuit is detected, SB 5 turns ON.

SI 5 contains a bitmap indicating on which device the affected output is located. When you include I/O expansion modules in your M90 hardware configuration, each module is assigned a place number, 0-7, according to its place in that configuration. In the bitmap, bits 0-7 correspond to these place numbers. Bit 8 is reserved for M90. A value of '1' indicates a short-circuited output.

In the bitmap below, short circuits have been detected in devices that are connected to expansion modules 1 and 3, and to the M90 itself.